In the related art, a method in which a buckling-restrained brace is fixed to a gusset plate (connected portion) of a structure and absorbs vibration energy when the structure vibrates by the impact of an earthquake, wind, or the like, has been evaluated.
For example, a buckling-restrained brace disclosed in patent document 1 as mentioned below includes an axial-force member (plate member) showing resistance against tensile force or compressive force applied in an axial direction, and a restrained member (buckling-restrained member) that is provided on the circumference of the axial-force member and restrains the buckling of the axial-force member. A bond-preventing film is provided in the gap between the axial-force member and the restrained member so as to prevent bonding therebetween. The axial-force member includes a plastic portion, the circumference of which is covered with the restrained member; a reinforcement portion that reinforces the rigidity of a portion of the axial-force member protruding from the restrained member; and a joint that is provided on the outside of the reinforcement portion and is joined to the structure.
The restrained member includes a reinforcement steel pipe (pipe member) that is provided on the circumference of the axial-force member, and concrete (filler) which fills the gap between the steel pipe and the axial-force member and which is hardened. Since the bond-preventing film is applied to the surface of the axial-force member, bonding between the axial-force member and hardened concrete or hardened mortar is prevented.
The buckling-restrained brace with such a configuration is fixed to a gusset plate using a pair of two splice plates. More specifically, the gusset plate is interposed between end portions of the two splice plates disposed facing each other, and the splice plates and the gusset plate are fixed together using bolts. The joint is interposed between the other end portions of the two splice plates, and the splice plates and the joint are fixed together using bolts.
When vibration energy is applied to the structure with such a configuration due to an earthquake, wind, or the like, tensile force or compressive force is applied to the buckling-restrained brace in the axial direction. The plastic portion of the axial-force member receives this force, is elastically deformed, and is further deformed plastically. As a result, the buckling-restrained brace absorbs the vibration energy.